In a radio frequency (RF) receiving system, the mixer is responsible for converting a RF signal to a baseband or an intermediate frequency (IF) band, which is a core module in a receiving link, and as a link of a RF signal and an IF signal, the power consumption level of the mixer occupies a considerable share in a receiving link. Therefore, in order to achieve low power consumption of the overall receiving circuit, the optimization design of the power consumption of the mixer is very crucial. Besides, the mixer requires to have sufficiently high conversion gain to restrain the influence of a high noise factor of the IF module on the entire receiving link.
In view of the above background, in recent years, a new structure referred to as a returnable mixer is proposed and applied. The main idea of the returnable mixer is that the RF transconductance stage is multiplexed and is used to amplify the RF signals and amplify the frequency-converted IF signals at the same time. However, in order to obtain a sufficiently high transconductance value at the RF, the transconductance stage generally uses a common-source open-loop structure in the design process of the returnable structure. The structure also has an effect of amplifying the IF signals, the linearity of the IF signal is severely restricted due to the limitation of the open-loop structure of the IF signal.